Extracellular matrix (ECM) proteins are important modulators of the cellular microenvironment. The interaction of cell-ECM is critical in regulation of cellular functions such as adhesion, migration, proliferation and differentiation. The disruption of cell-ECM structure affects the functionality of the cell and, hence, may result in apoptosis. Because of this reason, the naturally-occurring ECM proteins have been considered in medical applications such as tissue engineering and wound healing. Although the size of naturally-occurring ECM proteins ranges to upwards of several hundreds of kilodaltons, the functionality of these proteins arises generally from the presence of specific peptide sequences that are present within the ECM protein. One or more such sequences may be present and repeated through the ECM protein. As one example, a repeating pentapeptide sequence of Val-Pro-Gly-Val-Gly [SEQ ID NO:1] in elastin, the second most common ECM protein, attributes to its elasticity. Therefore, the polymers of these pentapeptides are reported to have potential in medical application. (See, Dan W. Urry and Asima Pattanaik, “Elastic Protein-based Materials in Tissue Reconstruction,” Artificial Organs, 831:32-46, 1997, and Dan W. Urry, Asima Pattanaik, Jie Xu, T. Cooper Woods, David T. McPherson and Timothy M. Parker, “Elastic Protein-based Polymers in Soft Tissue Augmentation and Generation,” J. Biomater. Sci. Polymer Edn., 9(10):1015-1048, 1998.)
The biological half-life of elastin protein is in the order of 70 years. The polymer containing pentapeptide, Val-Pro-Gly-Val-Gly, [SEQ ID NO:1] is expected to remain in a folded state at biological temperature hence it is also naturally resistant to the proteolytic degradation. It would be most advantageous for any scaffolding material to have the capacity to degrade once the natural tissue has been reconstructed at the site and the presence of the polymer is no longer needed. Therefore, addition of a degradable moiety or functionality to such polymers would have great potential for applications such as tissue engineering; wound healing, coatings, and drug delivery. By controlling the frequency and degradation half-life of the degradable functionality, these polymers can be engineered to have half-lives from a few days to years.